Switchable acoustic wave filter and related multiplexers

ABSTRACT

Aspects of this disclosure relate to a multiplexer that includes a switchable acoustic wave filter. The switchable acoustic wave filter can include one or more acoustic wave resonators, switchable acoustic wave resonators, and a switch configurable into at least a first state and a second state. The switch can select a different subset of the switchable acoustic wave resonators to filter a radio frequency signal together with at least the one or more acoustic wave resonators in the first state than in the second state. Related filters, radio frequency systems, wireless communication devices, and methods are also disclosed.

CROSS REFERENCE TO PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claimis identified in the Application Data Sheet as filed with the presentapplication are hereby incorporated by reference under 37 C.F.R. § 1.57.This application claims the benefit of priority of U.S. ProvisionalApplication No. 63/194,760, filed May 28, 2021 and titled “SWITCHABLEACOUSTIC WAVE FILTER AND RELATED MULTIPLEXERS,” U.S. ProvisionalApplication No. 63/208,600, filed Jun. 9, 2021 and titled “SWITCHABLEACOUSTIC WAVE FILTER,” and U.S. Provisional Application No. 63/208,620,filed Jun. 9, 2021 and titled “MULTIPLEXER WITH SWITCHABLE ACOUSTIC WAVEFILTER,” the disclosures of each of which are hereby incorporated byreference in their entireties and for all purposes.

BACKGROUND Technical Field

Embodiments of this disclosure relate to filters that includes acousticwave resonators.

Description of Related Technology

An acoustic wave filter can include a plurality of acoustic waveresonators arranged to filter a radio frequency signal. Example acousticwave filters include surface acoustic wave (SAW) filters and bulkacoustic wave (BAW) filters. BAW filters include BAW resonators. ExampleBAW resonators include film bulk acoustic wave resonators (FBARs) andBAW solidly mounted resonators (SMRs). SAW filters include SAWresonators. Example SAW resonators include temperature compensated SAWresonators, non-temperature compensated SAW resonators, and multilayerpiezoelectric substrate (MPS) SAW resonators.

Acoustic wave filters can be implemented in radio frequency electronicsystems. For instance, filters in a radio frequency front end of amobile phone can include acoustic wave filters. An acoustic wave filtercan be a band pass filter or a band stop filter. A plurality of acousticwave filters can be arranged as a multiplexer. For example, two acousticwave filters can be arranged as a duplexer. There are technicalchallenges associated with filtering signals with relatively closefrequencies using different filters of a multiplexer. In addition, thereare a variety of engineering tradeoffs associated with a filter thatfilters signals under different conditions.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

The innovations described in the claims each have several aspects, nosingle one of which is solely responsible for its desirable attributes.Without limiting the scope of the claims, some prominent features ofthis disclosure will now be briefly described.

One aspect of this disclosure is a switchable acoustic wave filter thatincludes a first acoustic wave resonator, a second acoustic waveresonator, and a switch configured to electrically connect the firstacoustic wave resonator to a node of the switchable acoustic wave filterin a first state and to electrically isolate the first acoustic waveresonator from the node of the switchable acoustic wave filter in asecond state. The switchable acoustic wave filter is configured toreceive a radio frequency signal, filter the radio frequency signal withat least the first acoustic wave resonator and the second acoustic waveresonator in the first state, and filter the radio frequency signal withat least the second acoustic wave resonator in the second state.

The switchable acoustic wave filter can have a different bandwidth inthe first state than in the second state. The switch can electricallyconnect an electrode of the first acoustic wave resonator to atermination impedance in the second state.

The switchable acoustic wave filter can include a third acoustic waveresonator. The switch can electrically isolate the third acoustic waveresonator from the node in the first state and electrically connect thethird acoustic wave resonator to the node in the second state. The firstacoustic wave resonator and the third acoustic wave resonator can havedifferent resonant frequencies.

The first acoustic wave resonator can be a series resonator.Alternatively, the first acoustic wave resonator can be a shuntresonator. The first acoustic wave resonator can be a bulk acoustic waveresonator in certain applications.

The switchable acoustic wave filter can be a band pass filter. Theswitchable acoustic wave filter can be a band stop filter. Theswitchable acoustic wave filter can be configured to filter a wirelesslocal area network signal. The switchable acoustic wave filter can beconfigured to filter a cellular signal. The switchable acoustic wavefilter can have a single switch loss.

The switchable acoustic wave filter can include a second switch and afourth acoustic wave resonator. The second switch can electricallyconnect and electrically isolate the fourth acoustic wave resonator froma second node of the switchable acoustic wave filter in differentstates.

Another aspect of this disclosure is a multiplexer that includes aswitchable acoustic wave filter and a second filter coupled to theswitchable acoustic wave filter at a common node. The switchableacoustic wave filter includes a first acoustic wave resonator, a secondacoustic wave resonator, and a switch. The switch is configured toelectrically connect the first acoustic wave resonator to a node of theswitchable acoustic wave filter in a first state and to electricallyisolate the first acoustic wave resonator from the node of theswitchable acoustic wave filter in a second state. The switchableacoustic wave filter is configured to receive a radio frequency signal,filter the radio frequency signal with at least the first acoustic waveresonator and the second acoustic wave resonator in the first state, andfilter the radio frequency signal with at least the second acoustic waveresonator in the second state.

The second filter can be a second switchable acoustic wave filterconfigured to selectively electrically couple an acoustic wave resonatorto a node of the second filter. The multiplexer can include a thirdfilter coupled to the common node.

The switchable acoustic wave filter can have a single switch loss. Thesecond state can be associated with co-existence.

Another aspect of this disclosure is a method of radio frequencyfiltering. The method includes filtering a radio frequency signal withat least a first acoustic wave resonator and a second acoustic waveresonator of a switchable acoustic wave filter in a first state, atoggling a state of the switchable acoustic wave filter from the firststate to a second state, and filtering a radio frequency signal with atleast the second acoustic wave resonator of the switchable acoustic wavefilter and not with the first acoustic wave resonator in the secondstate.

The toggling can change a bandwidth of the switchable acoustic wavefilter. The switchable acoustic wave filter can have a single switchloss.

Another aspect of this disclosure is a multiplexer with a switchableacoustic wave filter. The multiplexer includes a first filter configuredto receive a radio frequency signal and a second filter connected to thefirst filter at a common node. The first filter includes one or moreacoustic wave resonators, switchable acoustic wave resonators, and aswitch configurable into at least a first state and a second state. Theswitch is configured to select a different subset of the switchableacoustic wave resonators to filter the radio frequency signal togetherwith at least the one or more acoustic wave resonators in the firststate than in the second state.

The second state can be associated with co-existence. The first filtercan have lower performance associated with an operating band for thesecond state relative to the first state. The first filter can be a bandpass filter having a pass band, where the pass band covers a smallerfrequency range for the second state relative to the first state. Thefirst filter can be a band stop filter having a stop band, where thestop band covers a smaller frequency range for the second state relativeto the first state.

The switchable acoustic wave resonators can include series resonators.The switchable acoustic wave resonators can include shunt resonators.

A band edge of the first filter and a band edge of the second filter canbe closer in frequency in the first state of the switch than in thesecond state of the switch. The first state can be associated withassociated with the second filter being inactive and the second statecan be associated with co-existence.

The second filter can include a second switch and second switchableacoustic wave resonators. The first filter can be configured to move aband edge of a frequency response of the first filter by toggling theswitch between the first state and the second state. The second filtercan be configured to move a band edge of a frequency response of thesecond filter with the second switch. The multiplexer can include aninductor-capacitor circuit coupled between both the first filter and thesecond filter and an antenna node of the multiplexer. Theinductor-capacitor filter can attenuate a harmonic generated by theswitch.

The first filter can be a band pass filter and the second filter can bea band stop filter. The first filter can be a band stop filter and thesecond filter can be a band pass filter. The first filter and the secondfilter can be band pass filters.

The first filter can have a single switch loss. The first filter caninclude a second switch and second switchable acoustic wave resonators.

The first filter and the second filter can be configured to filter radiofrequency signals associated with different frequency bands. Thedifferent frequency bands can include a wireless local area network bandand a cellular band.

The first filter and the second filter can have respective band edgesthat are within 5 megahertz of each other.

The different subsets can include a first subset and a second subset,where the first subset consists of a first switchable acoustic waveresonator and the second subset consists of a second switchable acousticwave resonator.

Another aspect of this disclosure is a wireless communication thatincludes an antenna switch, an antenna, and an antenna-plexer. Theantenna-plexer including a first filter and a second filter coupled tothe first filter at a common node. The first filter is in a signal pathbetween the antenna switch and the antenna, a first filter configured toreceive a radio frequency signal, the first filter including one or moreacoustic wave resonators, switchable acoustic wave resonators, and aswitch configurable into at least a first state and a second state, theswitch configured to select a different subset of the switchableacoustic wave resonators to filter the radio frequency signal togetherwith at least the one or more acoustic wave resonators in the firststate than in the second state.

Another aspect of this disclosure is a switchable filter that includesone or more acoustic wave resonators, switchable acoustic waveresonators, and a switch configurable into at least a first state and asecond state. The switch is configured to select a different subset ofthe switchable acoustic wave resonators to filter a radio frequencysignal together with at least the one or more acoustic wave resonatorsin the first state than in the second state.

For purposes of summarizing the disclosure, certain aspects, advantagesand novel features of the innovations have been described herein. It isto be understood that not necessarily all such advantages may beachieved in accordance with any particular embodiment. Thus, theinnovations may be embodied or carried out in a manner that achieves oroptimizes one advantage or group of advantages as taught herein withoutnecessarily achieving other advantages as may be taught or suggestedherein.

The present disclosure relates to U.S. Patent Application No. ______[Attorney Docket SKYWRKS.1160A1], titled “SWITCHABLE ACOUSTIC WAVEFILTER,” filed on even date herewith, the entire disclosure of which ishereby incorporated by reference herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of this disclosure will now be described, by way ofnon-limiting example, with reference to the accompanying drawings.

FIGS. 1A, 1B, and 1C are schematic block diagrams of multiplexersaccording to embodiments.

FIG. 2 is a schematic diagram of a multiplexer with a switchable bandstop filter according to an embodiment.

FIG. 3 is a schematic diagram of a multiplexer with a switchable bandpass filter according to an embodiment.

FIG. 4 is a schematic diagram of a multiplexer with a switchable bandstop filter and a switchable band pass filter according to anembodiment.

FIG. 5A is a graph of insertion loss for the switchable band pass filtercomparing a full pass band and a pass band for accommodatingco-existence.

FIG. 5B is graph of a frequency response for a stop band of a switchableband stop filter comparing a full stop band and a stop band foraccommodating co-existence.

FIG. 6A is a graph of a frequency response of the switchable band passfilter comparing a full pass band and a pass band for accommodatingco-existence.

FIG. 6B is graph of a zoomed in frequency response of a switchable bandpass filter for a stop band comparing a full stop band and a stop bandfor accommodating co-existence.

FIG. 7 is a schematic diagram of a switchable band pass filter accordingto an embodiment.

FIG. 8 is a schematic diagram of a switchable band pass filter accordingto another embodiment.

FIG. 9 is a schematic diagram of a switchable band stop filter accordingto an embodiment.

FIG. 10 is a schematic diagram of a switchable band stop filteraccording to another embodiment.

FIG. 11 is a schematic diagram illustrating a switch configured toselectively electrically connect shunt resonators to a node of anacoustic wave filter according to an embodiment.

FIG. 12 is a schematic diagram illustrating a switch configured toselectively electrically connect series resonators to a node of anacoustic wave filter according to an embodiment.

FIG. 13 is a schematic block diagram of a multiplexer according to anembodiment.

FIG. 14A is a schematic diagram of a multiplexer with switchable filtersaccording to an embodiment.

FIG. 14B is a schematic diagram of a multiplexer with switchable filtersaccording to an embodiment.

FIG. 15 is a schematic diagram of a multiplexer with switchable filtersaccording to another embodiment.

FIG. 16 is a schematic diagram of a multiplexer with switchable filtersaccording to another embodiment.

FIG. 17 is a schematic diagram of a multiplexer with a switchable filteraccording to an embodiment.

FIG. 18 is a schematic diagram of a multiplexer with a switchable filteraccording to another embodiment.

FIG. 19 is a schematic diagram of a multiplexer with switchable filtersaccording to another embodiment.

FIG. 20 is a schematic diagram of a multiplexer with switchable filtersaccording to an embodiment.

FIG. 21 is a schematic diagram of a multiplexer with switchable filterswith termination impedances according to an embodiment.

FIG. 22 is a schematic diagram of a multiplexer with switchable filterswith termination impedances according to another embodiment.

FIG. 23 is a schematic diagram of a radio frequency system with amultiplexer according to an embodiment.

FIG. 24 is a schematic block diagram of a wireless communication devicethat includes a filter according to an embodiment.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

The following description of certain embodiments presents variousdescriptions of specific embodiments. However, the innovations describedherein can be embodied in a multitude of different ways, for example, asdefined and covered by the claims. In this description, reference ismade to the drawings where like reference numerals can indicateidentical or functionally similar elements. It will be understood thatelements illustrated in the figures are not necessarily drawn to scale.Moreover, it will be understood that certain embodiments can includemore elements than illustrated in a drawing and/or a subset of theelements illustrated in a drawing. Further, some embodiments canincorporate any suitable combination of features from two or moredrawings.

Antenna-plexers are multiplexers coupled between an antenna and aplurality of radio frequency signal paths. An antenna-plexer canfrequency domain multiplex signals having relatively close frequenciesin certain applications. An example antenna-plexer can diplex between amid-high band (MHB) signal and a 2.4 gigahertz (GHz) Wi-Fi signal. TheMHB signal can be a Band 40 signal, for example. Since the 2.4 GHz Wi-Fiband has a lower band edge at 2.4 GHz and a Band 40 signal has an upperband edge at 2.4 GHz, performance at the example antenna-plexer can besignificantly degraded at and/or around 2.4 GHz due to a zero frequencytransition. The antenna-plexer loading loss can be significant around2.4 GHz in this example.

To avoid such performance degradation, an antenna-plexer can includedesigns that have better performance for one band and sacrificeperformance of another band. For example, in a first design, theantenna-plexer can include a filter with a band edge around 2.36 GHz tocover the MHB up to 2.36 GHz and include another filter to cover a full2.4 GHz Wi-Fi band from 2.4 GHz to 2.48 GHz. A second design can coverthe full MHB range up to 2.4 GHz and compromise the lower band edge for2.4 GHz Wi-Fi. Since the two deigns have different bandwidths for theMHB path, two different filters can be implemented. In order to supportboth scenarios of MHB bandwidth coverage, switches can switch betweentwo separate filters as desired. Certain switchable designs involve twoswitches, one switch at the filter input and one at the filter output.Thus, two switch losses can be added the total filter loss in suchdesigns.

Aspects of this disclosure relate to switching one or more particularacoustic wave resonators to adjust bandwidth of a filter. Such filterscan employ acoustic wave resonator characteristics and switch a singleacoustic wave resonator or subset of acoustic wave resonators to adjustthe bandwidth. Accordingly, such a filter can be implemented with onlyone switch loss included in the filter total loss. Such a filter canhave a single switch loss. In addition, since only a single acousticwave resonator or subset of acoustic wave resonators are switched, thephysical layout and implementation is significantly smaller thansolutions with two complete filters. This reduction in physical area canbe significant in space-limited user equipment designs, such as cellularphones.

A switchable acoustic wave filter can include a first acoustic waveresonator, a second acoustic wave resonator, and a switch configured toelectrically connect the first acoustic wave resonator to a node of theswitchable acoustic wave filter in a first state and to electricallyisolate the first acoustic wave resonator from the node of theswitchable acoustic wave filter in a second state. The switchable filtercan receive a radio frequency signal, filter the radio frequency signalwith at least the first acoustic wave resonator and the second acousticwave resonator in the first state, and filter the radio frequency signalwith at least the second acoustic wave resonator in the second state.The switch can also electrically isolate a third acoustic wave resonatorfrom the node in the first state and electrically connect the thirdacoustic wave resonator to the node in the second state. Accordingly,the switch can select either the first acoustic wave resonator or thethird acoustic wave resonator to filter a radio frequency signal indifferent states.

Switchable filters disclosed herein can be implemented in multiplexers,such as antenna-plexers. One or more filters of a multiplexer can beswitchable to adjust bandwidth. Bandwidth can be adjusted by switchingin one or more acoustic wave resonators.

When two filters of a multiplexer have band edges that are relativelyclose to each other in the frequency domain, implementing at least oneof the two filters as a switchable filter can create separation betweenthe band edges of the two filters for co-existence and maintain fullbandwidth for at least one of the two filters without co-existence. Thiscan sacrifice performance for co-existence and otherwise achieve highfilter performance. Band edges of the two filters can be closer infrequency to each other without co-existence for switchable filtersdisclosed herein than for co-existence. Switchable acoustic wave filtersdisclosed herein can selectively electrically couple acoustic waveresonator(s) in the filter to adjust performance for co-existence andwithout co-existence.

A multiplexer can include a switchable acoustic wave filter. Themultiplexer can include a first filter and a second filter connected tothe first filter at a common node. The first filter can include one ormore acoustic wave resonators, switchable acoustic wave resonators, anda switch configurable into at least a first state and a second state.The switch can select a different subset of the switchable acoustic waveresonators to filter the radio frequency signal together with at leastthe one or more acoustic wave resonators in the first state than in thesecond state. Selecting the different subsets of switchable acousticwave resonators can move a band edge of the first filter in thefrequency domain. As an example, the different subsets can include afirst subset and a second subset, where the first subset includes only afirst switchable acoustic wave resonator and the second subset includesonly a second switchable acoustic wave resonator. The second filter canalso be switchable in certain applications. In certain applications, theswitchable acoustic wave filter can be a band pass filter. In some otherapplications, the switchable acoustic wave filter can be a band stopfilter.

Embodiments disclosed herein can achieve technical advantages over otherfilters and multiplexers. Embodiments disclosed herein can achievereduced filter switching loss. Certain switchable filters disclosedherein can have a single switch loss. Embodiments disclosed herein canbe implemented with a simpler architecture and fewer acoustic waveresonators than using separate filters for different conditions. Thiscan advantageously lead to smaller physical layout and lower cost.

FIGS. 1A, 1B, and 1C are schematic block diagrams of multiplexersaccording to embodiments. These multiplexers can include two acousticwave filters. One of these acoustic wave filters is a band pass filterand the other of the acoustic wave filters is a band stop filter. One orboth of these acoustic wave filters can be switchable. The examplemultiplexers illustrated in FIGS. 1A, 1B, and 1C are diplexers.

FIG. 1A illustrates a multiplexer 10 that includes a band pass filter 12and a switchable band stop filter 14. The band pass filter 12 and theswitchable band stop filter 14 can both be acoustic wave filters. Theband pass filter 12 can filter a first radio frequency (RF) signalpropagating between a first RF node RF1 and an antenna node ANT. Theantenna node ANT is a common node of the multiplexer 10 at which theband pass filter 12 and the switchable band stop filter are connected toeach other. The first RF signal can be a Wi-Fi signal, such as a 2.4 GHzWi-Fi signal. A Wi-Fi signal is an example of a wireless local areanetwork (WLAN) signal.

The switchable band stop filter 14 can filter a second RF propagatingbetween a second RF node RF2 and the antenna node ANT. The second RFsignal can be within a cellular operating band. The switchable band stopfilter 14 can block frequency components generally corresponding to thepass band of the band pass filter 12. Signals propagating between thesecond RF node RF2 and the antenna node ANT can be mid-high band (MHB)signals. The switchable band stop filter 14 can provide a stop band in apass band for a band pass filter, such as a 2.4 GHz Wi-Fi stop bandwithin a MHB band pass filter.

The switchable band stop filter 14 is operable in a first state and asecond state. In the first state, the switchable band stop filter 14 canhave a stop band corresponding to the full pass band of the band passfilter 12. In the second state, the switchable band stop filter 14 canhave a stop band where a lower band edge of the stop band is below thelower edge of the pass band of the band pass filter 12. The switchableband stop filter 14 can move a lower edge of the stop band away from thelower edge of the pass band of the band pass filter 12 for the secondstate relative to the first state. In the first state, the band passfilter 12 can be inactive and not filtering a radio frequency signal.The second state can be for co-existence.

FIG. 1B illustrates a multiplexer 15 that includes a switchable bandpass filter 16 and a band stop filter 18. The switchable band passfilter 16 and a band stop filter 18 can both be acoustic wave filters.The switchable band pass filter 16 is operable in a first state and asecond state. In the first state, the switchable band pass filter 16 canhave a pass band corresponding to a full operating band. In the secondstate, the switchable pass stop filter 16 can have a pass band where alower band edge of the stop band is above the lower end of the operatingband. The switchable band pass filter 12 can move a lower edge of thestop band away from the lower edge of the stop band of the band stopfilter 18 for the second state relative to the first state. In the firststate, the band stop filter 18 can be inactive and not filtering a radiofrequency signal. The second state can be for co-existence. The bandstop 18 can have a stop band that generally corresponds to the pass bandof the operating band associated with the switchable band pass filter16.

FIG. 1C illustrates a multiplexer 19 that includes a switchable bandpass filter 16 and a switchable band stop filter 14. In the multiplexer19, both the band pass filter and the band stop filter are switchable.For co-existence, the switchable band pass filter 16 can move an edge ofits pass band and the switchable band stop filter 14 can move an edge ofits stop band. In co-existence, the switchable band pass filter 16 canreduce its pass band and the switchable band stop filter 14 can reduceits stop band in the multiplexer 19. Without co-existence, theswitchable band pass filter 16 can have a full pass band and theswitchable band stop filter 14 can have a full stop band.

The band stop filters of FIGS. 1A, 1B, and 1C, can provide a stop bandin a larger pass band of a band pass filter, a low pass filter, or ahigh pass filter. As one example, the band stop filters of FIGS. 1A, 1B,and 1C can provide a 2.4 GHz Wi-Fi stop band in a band pass filter forpassing MHB signals.

Although the multiplexers of FIGS. 1A, 1B, and 1C each include band passfilter and a band stop filter, any suitable principles and advantages ofthese embodiments can be applied to a multiplexer with a plurality ofband pass filters and/or a multiplexer with a plurality band stopfilters.

Although moving certain band edges of filters are discussed withreference to FIGS. 1A to 1C, any suitable principles and advantagesdisclosed here can be applied to any band edge of an acoustic wavefilter or to two or more band edges of an acoustic wave filter.

Examples of the multiplexers of FIGS. 1A, 1B, and 1C will be discussedwith reference to FIGS. 2, 3, and 4 , respectively.

FIG. 2 is a schematic diagram of a multiplexer 20 with a band passfilter 22 and a switchable band stop filter 24 according to anembodiment. The multiplexer 20 is an example of the multiplexer 10 ofFIG. 1A. The illustrated multiplexer 20 is a diplexer. The multiplexer20 includes the band pass filter 22, the switchable band stop filter 24,and a passive impedance network 26.

The band pass filter 22 includes acoustic wave resonators R1, R2, R3,R4, R5, R6, and R7. These acoustic wave resonators can include one ormore surface acoustic wave (SAW) resonators, one or more bulk acousticwave (BAW) resonators, one or more other acoustic wave resonators, orany suitable combination thereof. As one example, acoustic waveresonators R1 to R7 can be BAW resonators. The band pass filter 22 canhave a pass band for passing a 2.4 GHz Wi-Fi signal, for example. Theoperating band for 2.4 GHz Wi-Fi can be from 2.40 GHz to 2.48 GHz.

As illustrated, the switchable band stop filter 24 includes a capacitorC1, an inductor L1, acoustic wave resonators R8, R9A, R9B, and a switch28. The acoustic wave resonators R8, R9A, R9B can include one or moreSAW resonators, one or more BAW resonators, one or more other acousticwave resonators, or any suitable combination thereof. As one example,acoustic wave resonators R8, R9A, R9B can be BAW resonators. Theacoustic wave resonators R9A, R9B are switchable acoustic waveresonators in the multiplexer 20.

The switch 28 selects between series acoustic wave resonators R9A andR9B to include in the group of acoustic wave resonators of theswitchable band stop filter 24 that filter an RF signal. In a firststate, the switch 28 can electrically connect a first series acousticwave resonator R9A to node N1 of the switchable band stop filter 24. Theswitch 28 can also electrically isolate a second series acoustic waveresonator R9B from the node N1 in the first state. The acoustic waveresonators R8 and R9A filter an RF signal in the first state. Theacoustic wave resonator R9B does not filter the RF signal in the firststate.

In a second state, the switch 28 can electrically connect the secondseries acoustic wave resonator R9B to the node N1. The switch 28 canalso electrically isolate the first series acoustic wave resonator R9Afrom the node N1 in the second state. The acoustic wave resonators R8and R9B filter an RF signal in the second state. The acoustic waveresonator R9A does not filter the RF signal in the second state. Asillustrated, the switchable band stop filter 24 is in second state.

In certain applications, the switch 28 can electrically connect bothseries acoustic wave resonators R9A and R9B to the node N1 in a thirdstate.

The series acoustic wave resonators R9A and R9B can one or moredifferent characteristics than each other. The one or more differentcharacteristics of the series acoustic wave resonators R9A and R9B caninclude one or more of resonant frequency, anti-resonant frequency,quality factor (Q), harmonic distortion, linearity, temperaturecoefficient of frequency (TCF), power handling, or the like.

The series acoustic wave resonators R9A and R9B can have differentresonant frequencies than each other. Accordingly, by toggling betweenthe first state and the second state, the switch 28 can adjust thebandwidth of the switchable band stop filter 24. In the first state, theswitchable band stop filter 24 can have a stop band corresponding to afull operating band associated with the band pass filter 22. In thesecond state, a lower band edge of the stop band of the switchable bandstop filter 24 can be moved to a higher frequency relative to for thefirst state. This can sacrifice some of the stop band corresponding tothe operating band associated with a radio frequency signal filtered bythe band pass filter. In the second state, the switchable band stopfilter 24 can have a reduced stop band. The second state can be forco-existence.

The passive impedance network 26 includes capacitors C2, C3, C4 andinductors L2, L2, and L4. The passive impedance network is coupledbetween each of the filters 22 and 24 and the antenna node ANT. Theantenna node ANT is a common node of the multiplexer 20 at which theband pass filter 22 and the switchable band stop filter 24 are connectedto each other. The passive impedance network 26 can provide filteringand/or impedance transformation.

The passive impedance network 26 can implement an inductor-capacitor(LC) filter. The LC filter can attenuate one or more harmonics generatedby a switch of a switchable filter. Accordingly, the one or moreharmonics can be suppressed at the antenna node ANT. In some instances,the LC filter can attenuate harmonics of a plurality of switches of amultiplexer. The LC filter can provide low pass filtering to protect aswitch and/or acoustic wave resonators of a multiplexer from one or morerelatively high power blocker signals. The passive impedance network 26can contribute to meeting an inter-modulation specification. The passiveimpedance network 26 can filter out inter-modulation distortion and/orone or more spurious signals. The passive impedance network 26 can beimplemented by any suitable inductor-capacitor circuit topology for aparticular application.

Multiplexers in accordance with any suitable principles and advantagesdisclosed herein can be implemented without the passive impedancenetwork 26 in various applications. Accordingly, a multiplexer with atleast one switchable filter in accordance with any suitable principlesand advantages disclosed herein can be implemented without an LC filtercoupled between the switchable filter and a common node or antenna nodeof the multiplexer.

FIG. 3 is a schematic diagram of a multiplexer with a switchable bandpass filter 32 and a band stop filter 34 according to an embodiment. Themultiplexer 30 is an example of the multiplexer 15 of FIG. 1A. Theillustrated multiplexer 30 is a diplexer. The multiplexer 30 includesthe switchable band pass filter 32, the band stop filter 34, and apassive impedance network 26.

The switchable band pass filter 32 includes acoustic wave resonators R1,R2, R3, R4, R5, R6A, R6B, and R7 and switch 38. The switchable band passfilter 32 is like the band pass filter 22 of FIG. 2 , except that theswitchable band pass filter 32 includes the switch 38 that canselectively electrically connect shunt resonators R6A and/or R6B to nodeN2. The shunt acoustic wave resonators R6A and R6B are switchableacoustic wave resonators in the multiplexer 30.

The shunt acoustic wave resonators R6A and R6B can one or more differentcharacteristics than each other. The one or more differentcharacteristics of the shunt acoustic wave resonators R6A and R6B caninclude one or more of anti-resonant frequency, resonant frequency,quality factor, harmonic distortion, linearity, TCF, power handling, orthe like. For example, the shunt resonators R6A and R6B can havedifferent resonant frequencies. Changing the state of the switch 38 canadjust the lower edge of the pass band of the switchable band passfilter 32.

The switch 38 selects which shunt acoustic wave resonator(s) R6A and/orR6B to include in the group of acoustic wave resonators of theswitchable band pass filter 32 that filter an RF signal. In a firststate, the switch 38 can electrically connect a first shunt acousticwave resonator R6A to node N2 of the switchable band pass filter 32. Theswitch 38 can also electrically isolate a second shunt acoustic waveresonator R6B from the node N2 in the first state. The acoustic waveresonators R1 to R5, R6A, and R7 filter an RF signal in the first state.The acoustic wave resonator R6B does not filter the RF signal in thefirst state.

In a second state, the switch 38 can electrically connect the secondshunt acoustic wave resonator R6B to the node N2. The switch 38 can alsoelectrically isolate the first shunt acoustic wave resonator R6A fromthe node N2 in the second state. The acoustic wave resonators R1 to R5,R6B, and R7 filter an RF signal in the second state. The acoustic waveresonator R6A does not filter the RF signal in the second state. In thesecond state, a lower band edge of the switchable band pass filter 32can be at a higher frequency than in the first state. This can sacrificeperformance at a lower part of the pass band for the second staterelative to the first state. Conversely, in the first state, the passband of the switchable band pass filter 32 can correspond to a fulloperating band. The second state can be for co-existence. Asillustrated, the switchable band pass filter 32 is in the second state.

In certain applications, the switch 38 can electrically connect bothshunt acoustic wave resonators R6A and R6B to the node N2 in a thirdstate.

The band stop filter 34 is like the switchable band stop filter 24 ofFIG. 2 , except that the band stop filter 34 is not switchable.Accordingly, the stop band of the band stop filter 34 can besubstantially fixed. In the band stop filter 34, series acoustic waveresonator R9 is included in place of the series acoustic wave resonatorsR9A and R9B and switch 28 from the switchable band stop filter 24.

FIG. 4 is a schematic diagram of a multiplexer 40 with a switchable bandstop filter 24 and a switchable band pass filter 32 according to anembodiment. In the multiplexer 40, both the band pass filter 32 and theband stop filter 24 are switchable. With the multiplexer 40, performancecan be reduced for the switchable band stop filter 24 and/or for theswitchable band pass filter 32 in co-existence.

In an example application, the switchable band pass filter 32 is a 2.4GHz Wi-Fi filter and the switchable band stop filter 24 is a band stopfilter blocking 2.4 GHz Wi-Fi for a MHB filter. In the switchable bandpass filter 32, the shunt acoustic wave resonator R6A can have aresonant frequency that will support a 2.4 GHz Wi-Fi pass band loweredge of 2.36 GHz and the shunt acoustic wave resonator R6B can have aresonant frequency that will support a 2.4 GHz Wi-Fi pass band loweredge of 2.40 GHz in the example application. In this example, when theshunt acoustic wave resonator R6A is selected, the pass band of theswitchable band pass filter 32 can be from 2.36 GHz to 2.48 GHz. Whenthe shunt acoustic wave resonator R6B is selected, the pass band of theswitchable band pass filter 32 can be from 2.43 GHz to 2.48 GHz or from2.40 GHz to 2.48 GHz. Accordingly, selecting the shunt acoustic waveresonator R6B instead of the shunt acoustic wave resonator R6A can movethe lower edge of the pass band up in frequency and sacrificeperformance for the lower part of the pass band of the switchable bandpass filter 32. This performance sacrifice can be made for co-existence,while the larger pass band can otherwise be used.

In the switchable band stop filter 24, the series acoustic waveresonator R9A can have an anti-resonant frequency that will support a2.4 GHz Wi-Fi 2.4 stop band edge of 2.36 GHz and the series acousticwave resonator R9B can have an anti-resonant frequency that will supporta 2.4 GHz Wi-Fi stop band edge of 2.40 GHz in the example application.In this example, the switch 28 toggling state and adjust a stop band ofthe switchable band stop filter 24 from 2.36 GHz to 2.48 GHz to 2.40 GHzto 2.48 GHz. A pass band of a filter that includes the switchable bandstop filter 24 can adjust from 1.71 GHz to 2.36 GHz to 1.71 GHz to 2.40GHz.

In certain instances, only one of the switchable band stop filter 24 orthe switchable band pass filter 32 can move its band edge by therespective switch 28 or 38 adjusting state. In some instances, theswitchable band stop filter 24 and the switchable band pass filter 32can move band edges away from each other by the switches 28 and 38adjusting state. In some instances, the switchable band stop filter 24and the switchable band pass filter 32 can shift band edges in the samedirection in frequency to maintain the same or a similar frequencyseparation from each other by the switches 28 and 38 adjusting state.

The multiplexer 40 was simulated in two different states. In a firststate, a full 2.4 GHz Wi-Fi pass band is provided for a band pass filterand a corresponding stop band is also provided for another filter. In asecond state, the pass band and stop band are adjusted for co-existence.FIG. 5A is a graph of insertion loss for the switchable band pass filter32 for the first state and the second state. FIG. 5B is a graph of thatshows a stop band associated with the switchable band stop filter 24 forthe first state and the second state.

FIG. 5A is a graph of insertion loss for the switchable band pass filter32 comparing a full pass band and a pass band for accommodatingco-existence. FIG. 5A plots simulation results for insertion loss for a2.4 GHz Wi-Fi band. A first curve 52 corresponds to insertion loss for afull 2.4 GHz Wi-Fi band for the first state. A second curve 54corresponds to insertion loss for 2.4 GHz Wi-Fi band for co-existence inthe second state. FIG. 5A indicates that insertion loss is sacrificed atthe lower end of the 2.4 GHz Wi-Fi band for co-existence in the secondstate. The pass band of the switchable band pass filter 32 can bereduced at the lower end of the 2.4 GHz Wi-Fi band for co-existence inthe second state.

FIG. 5B is graph of a frequency response for a stop band of theswitchable band stop filter 24 comparing a full stop band and a stopband for accommodating co-existence. A first curve 56 corresponds to afrequency response with a stop band for a full 2.4 GHz Wi-Fi band forthe first state. A second curve 58 corresponds to a frequency responsewith a smaller stop band for a 2.4 GHz Wi-Fi band for co-existence inthe second state. FIG. 5B indicates that a lower end of the 2.4 GHzWi-Fi stop band is sacrificed for co-existence in the second state.

FIG. 6A is a graph of a frequency response of the switchable band passfilter 32 comparing a full pass band and a pass band for accommodatingco-existence. A first curve 62 is for a full 2.4 GHz Wi-Fi pass band forthe first state. A second curve 64 is for a reduced 2.4 GHz Wi-Fi bandfor co-existence in the second state. The switch 38 selecting adifferent shunt acoustic wave resonator R6A or R6B can cause the stateof the switchable band pass filter 32 to toggle between the first stateand the second state. The simulation results indicate that a lower bandedge of the pass band moves up in frequency for the second state. Thesimulation results indicate that performance in the second state atlower band edge and lower part of the 2.4 GHz Wi-Fi pass band issacrificed for the second state compared to the first state. In thegraph of FIG. 6A, the pass band is from about 2.4 GHz to 2.48 GHz in thefirst state and from about 2.43 GHz to 2.48 GHz in the second state.

FIG. 6B is graph of a zoomed in frequency response of the switchableband pass filter 24 for a stop band comparing a full stop band and astop band for accommodating co-existence. A first curve 66 is for a full2.4 GHz Wi-Fi stop band for the first state. A second curve 68 is for areduced 2.4 GHz Wi-Fi stop band for co-existence in the second state.The switch 28 selecting a different shunt acoustic wave resonator R9A orR9B can cause the state of the switchable band stop filter 28 to togglebetween the first state and the second state. The simulation resultsindicate that a lower band edge of the stop band moves to a higherfrequency for the second state compared to the first state. Thesimulation results indicate that performance in the second state at partof a stop band is sacrificed for the second state compared to the firststate.

Any suitable principles and advantages of the switchable filtersdisclosed herein can be implemented in standalone filters and/or or anyother suitable multiplexers. FIGS. 7 and 8 illustrate examples ofswitchable band pass filters. FIGS. 9 and 10 illustrate examples ofswitchable band stop filters. In these filters, any suitable acousticwave resonators can be implemented. As an example, BAW resonators can beincluded in any of the filters of FIGS. 7 to 10 . The example filters ofFIGS. 7 to 10 are arranged to adjust one band edge in a frequencydomain. Any suitable principles and advantages disclosed herein can beimplemented to adjust two or mode band edges in a frequency domain. Forexample, a band pass filter can include features of FIGS. 7 and 8 toadjust two edges of a pass band. As another example, a band stop filtercan include features of FIGS. 9 and 10 to adjust two edges of a stopband. A filter can include any suitable combination of features of theembodiments of FIGS. 7 to 10 .

One or more switchable filters in accordance with any suitableprinciples and advantages disclosed herein can be configured to filter aradio frequency signal in a fifth generation (5G) New Radio (NR)operating band within Frequency Range 1 (FR1). FR1 can be from 410megahertz (MHz) to 7.125 gigahertz (GHz), for example, as specified in acurrent 5G NR specification. One or more filters in accordance with anysuitable principles and advantages disclosed herein can be included in afilter configured to filter a radio frequency signal in a fourthgeneration (4G) Long Term Evolution (LTE) operating band. One or morefilters in accordance with any suitable principles and advantagesdisclosed herein can be included in a filter having a pass band thatincludes a 4G LTE operating band and a 5G NR operating band. One or moreswitchable filters in accordance with any suitable principles andadvantages disclosed herein can be configured to filter a radiofrequency signal in a wireless local area network band, such as a Wi-Fiband. One or more switchable filters in accordance with any suitableprinciples and advantages disclosed herein can have a pass bandcorresponding to a 5G NR operating band, a 4G LTE operating band, a 4GLTE operating band and a 5G operating band, or a wireless local areanetwork operating band. One or more switchable filters in accordancewith any suitable principles and advantages disclosed herein can have astop band corresponding to a 5G NR operating band, a 4G LTE operatingband, a 4G LTE operating band and a 5G operating band, or a wirelesslocal area network operating band.

Certain embodiments may be discussed with reference to switchingacoustic wave resonators to adjust bandwidth of a filter and/or locationof a band edge of the filter in a frequency domain. Any suitableprinciples and advantages disclosed herein can be applied to switchingacoustic wave resonators to adjust one or more other suitablecharacteristic of a filter, such as one or more of linearity, harmonicdistortion, power handling, or the like. For instance, acoustic waveresonators with different linearity characteristics can be switched inand/or out of a filter to achieve different linearity performance indifferent states. As another example, acoustic wave resonators withdifferent characteristics can be switched in and/or out of a filter toachieve different power handling performance in different states.

FIG. 7 is a schematic diagram of a switchable band pass filter 32according to an embodiment. The switchable band pass filter 32 hasswitchable shunt acoustic wave resonators R6A and R6B. In a band passfilter, shunt acoustic wave resonators typically impact a lower edge ofa pass band. The switch 38 can select shunt acoustic wave resonator R6Ain a first state and select shunt acoustic wave resonator R6B in asecond state. This can adjust the lower edge of the pass band for thedifferent states of the switchable band pass filter 32. The seriesacoustic wave resonator R7 can be a first acoustic wave resonator of theswitchable band pass filter 32 from a common node of a multiplexer, forexample, as shown in FIGS. 3 and 4 . Alternatively, the series acousticwave resonator R1 can be a first acoustic wave resonator of theswitchable band pass filter 32 from a common node of a multiplexer forsome other applications. With the series acoustic wave resonator R1 asthe first acoustic wave resonator from a common node of a multiplexer,any noise and/or distortion from the switch 38 can be further from thecommon node. In some instances, the switch 38 can select both shuntacoustic wave resonators R6A and R6B in a third state. In the switchableband pass filter 32, there is only a single switch loss.

FIG. 8 is a schematic diagram of a switchable band pass filter 80according to another embodiment. The switchable band pass filter 80 hasswitchable series acoustic wave resonators R7A and R7B. In a band passfilter, series acoustic wave resonators typically impact an upper edgeof a pass band. A switch 88 can select series acoustic wave resonatorR7A in one state and select series acoustic wave resonator R7B inanother state. This can adjust the upper edge of the pass band fordifferent states of the switchable band pass filter 80. For example, theswitchable band pass filter 80 can lower the upper band edge of a passband for co-existence with another frequency band above the pass band.The series acoustic wave resonator R7A and/or R7B can be a firstacoustic wave resonator of the switchable band pass filter 80 from acommon node of a multiplexer. Alternatively, the series acoustic waveresonator R1 can be a first acoustic wave resonator of the switchableband pass filter 80 from a common node of a multiplexer for some otherapplications. In some instances, the switch 88 can select both seriesacoustic wave resonators R7A and R7B in a third state. In the switchableband pass filter 80, there is only a single switch loss.

FIG. 9 is a schematic diagram of a switchable band stop filter 24according to an embodiment. The switchable band stop filter 24 hasswitchable series acoustic wave resonators R9A and R9B. In a band stopfilter, series acoustic wave resonators typically impact a lower edge ofa stop band. The switch 28 can select series acoustic wave resonator R9Ain a first state and select series acoustic wave resonator R9B in asecond state. This can adjust the lower edge of the stop band for thedifferent states of the switchable band stop filter 24. In someinstances, the switch 28 can select both series acoustic wave resonatorsR9A and R9B in a third state. In the switchable band stop filter 24,there is only a single switch loss.

FIG. 10 is a schematic diagram of a switchable band stop filter 100according to another embodiment. The switchable band stop filter 100 hasswitchable shunt acoustic wave resonators R8A and R8B. In a band stopfilter, shunt acoustic wave resonators typically impact an upper edge ofa stop band. A switch 108 can select shunt acoustic wave resonator R8Ain one state and select shunt acoustic wave resonator R8B in anotherstate to adjust the upper edge of the stop band for different states ofthe switchable band stop filter 100. For example, the switchable bandstop filter 100 can lower the upper band edge of a stop band forco-existence with another frequency band above the stop band. In someinstances, the switch 108 can select both shunt acoustic wave resonatorsR8A and R8B in a third state. In the switchable band stop filter 100,there is only a single switch loss.

Although embodiments disclosed herein may relate to filters with aswitch configured to selectively couple different acoustic waveresonators to a node of a filter, any suitable principles and advantagesdisclosed herein can implemented in applications with an acoustic waveresonator with fixed connection to a node of a filter and one or moreother acoustic wave resonators that can be connected in parallel withthe acoustic wave resonator by a switch as desired. For example, in somesuch applications, there can be one state where just a shunt acousticwave resonator with the fixed connection is connected to a node and oneor more other states with at least one other shunt acoustic waveresonator connected in parallel with the shunt acoustic wave resonatorvia a switch. As another example, in some applications, there can be onestate where just a series acoustic wave resonator with the fixedconnection is connected to a node and one or more other states with atleast one other series acoustic wave resonator connected in parallelwith the series acoustic wave resonator via a switch.

Although embodiments disclosed herein may relate to filters with aswitch configured to selectively couple two different acoustic waveresonators to a node of a filter, any suitable principles and advantagesdisclosed herein can be implemented with a switch configured toselectively couple three or more acoustic wave resonators to a node of afilter. FIGS. 11 and 12 illustrate examples of switches configured toselectively couple one or more of at least three switches to a node of afilter. Any suitable principles and advantages of these embodiments canbe implemented together with each other and/or together with anysuitable features of one or more other embodiments disclosed herein.

FIG. 11 is a schematic diagram illustrating a switch 118 configured toselectively electrically connect switchable shunt acoustic waveresonators RSHA, RSHB, RSHN to a node NSH of an acoustic wave filterstage 110 according to an embodiment. The switch 118 can select adifferent subset of the switchable acoustic wave resonators RSHA to RSHNto filter the radio frequency signal together with at least the seriesacoustic wave resonator RSE in a first state than in a second state.Selecting the different subsets of switchable acoustic wave resonatorsRSHA to RSHN can move a band edge of a filter that includes the filterstage 110 in the frequency domain. The switch 118 can electricallyconnect a single one of the shunt acoustic wave resonators RSHA, RSHB,RSHN to the node NSH at a time. The switch 118 can alternatively oradditionally electrically connect two or more of the shunt acoustic waveresonators RSHA, RSHB, RSHN to the node NSH at a time. The illustratedfilter stage 110 also includes series acoustic wave resonator RSE. Thefilter stage 110 can be included in a filter with one or more otheracoustic wave resonator filter stages. Alternatively or additionally,the filter stage 110 can be included in filter with aninductor-capacitor circuit.

FIG. 12 is a schematic diagram illustrating a switch 128 configured toselectively electrically connect switchable series acoustic waveresonators RSEA, RSEB, RSEN to a node NSE of an acoustic wave filterstage 120 according to an embodiment. The switch 128 can select adifferent subset of the switchable acoustic wave resonators RSEA to RSENto filter the radio frequency signal together with at least the shuntacoustic wave resonator RSH in a first state than in a second state.Selecting the different subsets of switchable acoustic wave resonatorsRSEA to RSEN can move a band edge of a filter that includes the filterstage 120 in the frequency domain. The switch 128 can electricallyconnect a single one of the series acoustic wave resonators RSEA, RSEB,RSEN to the node NSE at a time. The switch 128 can alternatively oradditionally electrically connect two or more of the series acousticwave resonators RSEA, RSEB, RSEN to the node NSE at a time. Theillustrated filter stage 120 also includes shunt acoustic wave resonatorRSH. The filter stage 120 can be included in a filter with one or moreother acoustic wave resonator filter stages. Alternatively oradditionally, the filter stage 120 can be included in filter with aninductor-capacitor circuit.

As discussed above, any suitable principles and advantages disclosedherein can be implemented in any suitable multiplexers. Any subset offilters of such multiplexers or all filters of such multiplexers can beswitchable. Embodiments of triplexers with one or more switchableacoustic wave filters will be discussed with reference to FIGS. 13 to 22. In these embodiments, bandwidth of a switchable acoustic wave filtercan be adjusted by a switch selectively coupling one or more acousticwave resonators to a node of the filter. Any suitable combination offeatures of these triplexers can be implemented together with each otherand/or any other suitable combination of features disclosed herein.

FIG. 13 is a schematic block diagram of a multiplexer 130 according toan embodiment. The multiplexer 130 is a triplexer. As illustrated, themultiplexer 130 includes a first switchable acoustic wave filter 132, asecond switchable acoustic wave filter 134, and third filter 136. Theillustrated filters 132, 134, and 136 are coupled to each other at anantenna node ANT. The multiplexer 130 can be an antenna-plexer.

The first switchable acoustic wave filter 132 can be a band pass filter.The first switchable acoustic wave filter 132 can be a band pass filterconfigured to pass 2.4 GHz Wi-Fi signals. The bandwidth of the firstswitchable acoustic wave filter 132 can be adjusted in accordance withany suitable principles and advantages disclosed herein. The firstswitchable acoustic wave filter 132 is shown in block form and theillustrated symbol represents that the first switchable acoustic wavefilter 132 can change bandwidth in different states. The same outputnode of the first switchable acoustic wave filter 132 can be coupled tothe antenna node ANT in the different states.

The second switchable acoustic wave filter 134 can be a MHB filter. Thesecond switchable acoustic wave filter 134 can include a notch in itspass band for a frequency band corresponding to the first switchableacoustic wave filter 132. For example, the second switchable acousticwave filter 134 can have aa notch for a 2.4 GHz Wi-Fi band. The notchbandwidth of the second switchable acoustic wave filter 134 can beadjusted in accordance with any suitable principles and advantagesdisclosed herein. The second switchable acoustic wave filter 134 isshown in block form and the illustrated symbol represents that thesecond switchable acoustic wave filter 134 can change notch bandwidth indifferent states. The same output node of the second switchable acousticwave filter 134 can be coupled to the antenna node ANT in the differentstates.

The third filter 136 can be a high pass filter. The third filter 136 canbe an ultra high band (UHB) filter. The third filter can be aninductor-capacitor filter that includes inductors and capacitors, orinductors and capacitors plus one or more acoustic wave resonators.

Examples of the multiplexer 130 are discussed with reference to FIGS.14A-16, 19, and 20 . Examples of a similar multiplexer with oneswitchable acoustic wave filter are discussed with reference to FIGS. 17and 18 . Any suitable combination of features of the embodiments ofFIGS. 13 to 20 can be implemented together with each other.

FIG. 14A is a schematic diagram of a multiplexer 140 with switchablefilters according to an embodiment. The multiplexer 140 is an example ofthe multiplexer 130 of FIG. 13 . As illustrated, the multiplexer 140includes a first switchable acoustic wave filter 142, a secondswitchable acoustic wave filter 145, a third filter 148, and a passiveimpedance network 26.

The first switchable acoustic wave filter 142 includes switches 143 and144 each configured to selectively electrically connect acoustic waveresonators to respective nodes of the first switchable acoustic wavefilter 142. The first switchable acoustic wave filter 142 also includesacoustic wave resonators R0, R1A, R1B, R2, R3, R4, R5, R6, R7A, and R7Band series inductor L5. The acoustic wave resonators R1A, R1B, R7A, andR7B are switchable acoustic wave resonators.

The switches 143 and 144 can connect different acoustic wave resonatorsto nodes of the filter to adjust bandwidth of the first switchablefilters for different states. For example, in a first state, the switch143 can connect acoustic wave resonator R1A to the acoustic waveresonator R0 and electrically isolate acoustic wave resonator R1B fromthe acoustic wave resonator R0. The switch 144 can connect acoustic waveresonator R7A to the passive impedance network 26 and electricallyisolate acoustic wave resonator R7B from the passive impedance network26 in the first state. In this example, the switch 143 can connectacoustic wave resonator R1B to the acoustic wave resonator R0 andelectrically isolate acoustic wave resonator R1A from the acoustic waveresonator R0 in the second state. The switch 144 can connect acousticwave resonator R7B to the passive impedance network 26 and electricallyisolate acoustic wave resonator R7A from the passive impedance network26 in the second state.

In the multiplexer 140, the first switchable acoustic wave filter 142and the second switchable acoustic wave filter 145 are coupled to theantenna node ANT by way of the passive impedance network 26. The passiveimpedance network can implement an LC filter. The LC filter canattenuate one or more harmonics generated by one or more switches (e.g.,the switches 144 and/or 146) of the switchable acoustic wave filters 142and/or 145. This can suppress the one or more harmonics at the antennanode ANT. The LC filter can suppress intermodulation distortion and/orspurious responses. The LC filter can provide low pass filtering toprotect one or more switches and/or acoustic wave resonators of themultiplexer 140 from one or more relatively high power blocker signals.

In certain applications, the first switchable acoustic wave filter 142can be a band pass filter for a 2.4 GHz Wi-Fi band. As an example, theswitches 143 and 144 can adjust a pass band of the first switchableacoustic wave filter 142 from 2.40 GHz to 2.48 GHz in a first state to2.40 GHz to 2.46 GHz in a second state. The first state can correspondto passing the full 2.4 GHz Wi-Fi band in this example. In the secondstate, high isolation can be provided for Band 53 (2.4835 GHz to 2.495GHz) while performance at an upper end of the 2.4 GHz Wi-Fi band can besacrificed in this example.

The second switchable acoustic wave filter 145 includes a switch 146configured to selectively electrically connect different acoustic waveresonators to a node of the second switchable acoustic wave filter 145.The switchable acoustic wave filter 145 includes capacitors C1 and C7,inductors L1, L6, and L7, and acoustic wave resonators R8A, R8B, R9, andR10. The acoustic wave resonators R8A and R8B are switchable acousticwave resonators. The switch 146 can connect different acoustic waveresonators to the node, and adjust stop band bandwidth of the secondswitchable filter 145 for different states. In certain applications, theswitchable acoustic wave filter 145 can be a band stop pass filterconfigured to provide a stop band corresponding to a 2.4 GHz Wi-Fi bandfor a MHB filter. As an example, the switch 146 can adjust the stop bandof second first switchable acoustic wave filter 145 from 2.40 GHz to2.48 GHz in a first state to 2.40 GHz to 2.46 GHz in a second state. Theswitch 146 can electrically connect acoustic wave resonator R8A to anode between acoustic wave resonators R9 and R10 in the first state andelectrically isolate acoustic wave resonator R8B from the node betweenacoustic wave resonators R9 and R10 in the first state. The switch 146can electrically connect acoustic wave resonator R8B to the node betweenacoustic wave resonators R9 and R10 in the second state and electricallyisolate acoustic wave resonator R8A from the node between acoustic waveresonators R9 and R10 in the second state. The first state cancorrespond to passing the full 2.4 GHz Wi-Fi band in this example. Inthe second state, high isolation can be provided for Band 53 while stopband performance at an upper end of the 2.4 GHz Wi-Fi band can besacrificed in this example.

The third filter 148 can be a high pass filter. The third filter canpass an UHB signal. As illustrated, the third filter 148 is aninductor-capacitor filter. The illustrated third filter 148 includescapacitors C8 and C9 and inductors L8, L9, and L10. The third filter 148can include any suitable type of inductors and any suitable type ofcapacitor. The third filter 148 can be implemented with any suitableinductor-capacitor filter topology, any suitable acoustic wave resonatorfilter topology, or any suitable filter topology that includes aninductor-capacitor circuit and one or more acoustic wave resonators. Thethird filter 148 is connected to the first switchable acoustic wavefilter 142 and the second switchable acoustic wave filter 145 at acommon node of the multiplexer 140. The common node can be an antennanode ANT as illustrated.

FIG. 14B is a schematic diagram of a multiplexer 149 with switchablefilters according to another embodiment. The multiplexer 149 is like themultiplexer 140 of FIG. 14A, except that acoustic wave resonator R7 isimplemented in place of the switch 144 and corresponding switchableacoustic wave resonators R7A and R7B in a switchable acoustic wavefilter 147 of FIG. 14B. In the switchable acoustic wave filter 147, theswitch 143 is located away from the antenna node ANT. Accordingly,intermodulation distortion and/or harmonic distortion associated withthe switch 143 are introduced away from the antenna node ANT. Suchintermodulation distortion and/or harmonic distortion can be attenuatedat the antenna node ANT.

FIG. 15 is a schematic diagram of a multiplexer 150 with switchablefilters according to another embodiment. The multiplexer 150 is like themultiplexer 140 of FIG. 14A, except that a switch 154 and correspondingswitchable acoustic wave resonators R5A and R5B are located in adifferent location in the filter topology of a first switchable filter152 compared to the switch 143 and corresponding switchable acousticwave resonators R1A and R1B of the first switchable filter 142 of FIG.14A. A switch configured to selectively electrically connect acousticwave resonators to a node of a filter can be located at any suitablelocation in a filter topology for a particular application. Two or moreswitches configured to selectively electrically connect acoustic waveresonators to a respective node of a filter can be located at anysuitable locations in a filter topology for a particular application.

FIG. 16 is a schematic diagram of a multiplexer 160 with switchablefilters according to another embodiment. In the multiplexer 160, a firstswitchable filter 162 includes one switch 144 to selectivelyelectrically connect switchable acoustic wave resonators R7A and R7B toa node of the first switchable filter 162. The switch 144 can adjustbandwidth of the first switchable filter 162. The multiplexer 160 alsoincludes a second switchable filter. The second switchable filterincludes switches 163 and 164 that together select a first sub filter165 or a second sub filter 166. Each of the sub filters 165 and 166include at least one filter stage and a plurality of acoustic waveresonators. As illustrated, the first sub filter 165 includes acousticwave resonators R11 and R12. The illustrated second sub filter 166includes acoustic wave resonators R8, R9, and R10 and aninductor-capacitor circuit. The inductor-capacitor circuit of the secondsub filter can include inductors L6 and L7 and capacitor C7.

FIG. 17 is a schematic diagram of a multiplexer 170 with a switchablefilter according to an embodiment. The multiplexer 170 includes a singleswitchable filter. In the multiplexer 170, the first switchable filter162 is a switchable band pass filter. In the multiplexer 170, the secondfilter 175 is fixed rather than switchable. The second filter 175 can bethe same or similar to the second sub filter 166 of FIG. 16 . Switchingthe first switchable filter 162 to adjust bandwidth of the firstswitchable filter 162 together with the stop band of produced by thesecond filter 175 can be sufficient to meet performance specificationsin certain applications.

FIG. 18 is a schematic diagram of a multiplexer 180 with a switchablefilter according to another embodiment. The multiplexer 180 is like themultiplexer 170 of FIG. 17 , except that the first switchable acousticwave filter 142 of the multiplexer 180 includes two switches andcorresponding switchable acoustic wave resonators. The multiplexer 180is like the multiplexer 140 of FIG. 14A, except that the second filter175 of the multiplexer 180 is fixed rather than switchable.

FIG. 19 is a schematic diagram of a multiplexer 190 with switchablefilters according to another embodiment. The multiplexer includes afirst switchable filter 192 with switches 193 and 144 and switchableacoustic wave resonators R3A, R3B, R7A, and R7B. The multiplexer 190 islike the multiplexers 140 and 150 of FIGS. 14A and 15 , respectively,except that the first switchable acoustic wave filter 192 of themultiplexer 190 includes a switch 193 and corresponding switchableacoustic wave resonators R3A and R3B at different locations in thefilter topology. The multiplexer 190 is like the multiplexer 140 of FIG.14A, except that the switch 193 and corresponding switchable acousticwave resonators R3A and R3B are in a different location in the filtertopology than the switch 143 and corresponding switchable acoustic waveresonators R1A and R1B of the multiplexer 140. The multiplexer 190 islike the multiplexer 150 of FIG. 15 , except that the switch 193 andcorresponding switchable acoustic wave resonators R3A and R3B are in adifferent location in the filter topology than the switch 154 andcorresponding switchable acoustic wave resonators R5A and R5B of themultiplexer 150.

FIG. 20 is a schematic diagram of a multiplexer 200 with switchablefilters according to an embodiment. The multiplexer 200 is like themultiplexers 140, 150, and 190, except the multiplexer 200 includes afirst switchable acoustic wave filter 162 with a single switch 144.

In switchable filters disclosed herein, switchable acoustic waveresonators can have one end electrically connected to a filter andanother end electrically isolated from the filter in certain states. Atermination impedance can be electrically connected in parallel with oneor more switchable acoustic wave resonators via a switch when the one ormore acoustic wave resonators are not selected. Such a terminationimpedance can improve spurious performance. Example terminationimpedances and related switches are discussed with reference to FIGS. 21and 22 . Any suitable principles and advantages discussed with referenceto FIGS. 21 and/or 22 can be implemented in accordance with any suitableprinciples and advantages of any of the embodiments discussed above.

FIG. 21 is a schematic diagram of a multiplexer 210 with switchablefilters with termination impedances according to an embodiment. In themultiplexer 210, a first switchable filter 212 includes a switchablecircuit 213. A switch 214 of the switchable circuit 213 can selectivelyconnect switchable acoustic wave resonators R7A, R7B to a node of thefirst switchable filter 212. The switch 214 can also electricallyconnect an unselected switchable acoustic wave resonator to atermination impedance 215. The termination impedance 215 can be anysuitable termination impedance, such as one or more resistors, one ormore capacitors, one or more inductors, one or more resistors connectedto one or more inductors, the like, or any suitable combination thereof.The termination impedance 215 can include any suitable passive impedanceelement(s) to provide desirable performance of spurs in a pass bandand/or a rejection band. The termination impedance 215 can be 50 Ohms,for example. The switch 214 can connect the termination impedance 215 inparallel with an unselected switchable series acoustic wave resonator.

In the switchable circuit 213, the termination impedance 215 isconnectable in parallel with a single switchable acoustic wave resonatorR7A. The switch 214 can selectively electrically connect an electrode ofthe switchable acoustic wave resonator R7A to the termination impedance215. The switch 214 can connect the termination impedance 215 inparallel with the switchable acoustic wave resonator R7A when unselectedand electrically isolate an end of the termination impedance 215 fromthe switchable acoustic wave resonator R7A when selected. Asillustrated, in FIG. 20 , the switchable acoustic wave resonator R7A isselected and an end of the termination impedance 215 is electricallyisolated from the switchable acoustic wave resonator R7A. Thetermination impedance 215 can be connectable in parallel with aswitchable acoustic wave resonator R7A that is selected for a mode wherethe pass band of the filter 212 is reduced. The termination impedance215 can be connectable in parallel with a switchable acoustic waveresonator R7A that is selected for a co-existence mode. The terminationimpedance 215 can be connectable in parallel with a switchable acousticwave resonator R7A selectively.

The multiplexer 210 also includes a second switchable filter 216 with aswitchable circuit 217. A switch 218 of the switchable circuit 217 canselectively connect switchable acoustic wave resonators R8A, R8B to anode of the second switchable filter 216. The switch 218 can alsoelectrically connect an unselected acoustic wave resonator to atermination impedance 219. The termination impedance 219 can be anysuitable termination impedance, such as one or more resistors, one ormore capacitors, one or more inductors, one or more resistors connectedto one or more inductors, the like, or any suitable combination thereof.The termination impedance 219 can include any suitable passive impedanceelement(s) to provide desirable performance of spurs in a pass bandand/or a rejection band. The termination impedance 219 can be 10 Ohms,for example. The switch 218 can connect the termination impedance 219 inparallel with an unselected shunt acoustic wave resonator.

In the switchable circuit 217, the termination impedance 219 isconnectable in parallel with a single switchable acoustic wave resonatorR8A. The switch 218 can selectively electrically connect an electrode ofthe switchable acoustic wave resonator R8A to the termination impedance219. The switch 218 can connect the termination impedance 219 inparallel with the switchable acoustic wave resonator R8A when theswitchable acoustic wave resonator R8A is unselected and electricallyisolate an end of the termination impedance 219 from the switchableacoustic wave resonator R8A when the switchable acoustic wave resonatorR8A is selected. As illustrated, in FIG. 20 , the switchable acousticwave resonator R8A is selected and an end of the termination impedance219 is electrically isolated from the switchable acoustic wave resonatorR8A. The termination impedance 219 can be connectable in parallel with aswitchable acoustic wave resonator R8A that is selected for a mode wherea stop band is reduced, for a co-existence mode, for a relatively smallpercentage of the time, the like, or any suitable combination thereof.

In the switchable circuits 213 and 217, acoustic wave resonators R7A,R7B, R8A, and R8A are illustrated as two acoustic wave resonators inseries with each other. An individual acoustic wave resonator can besplit into series resonators or parallel resonators. Any of the acousticwave resonators shown in the drawings can be implemented by acousticwave resonators in series with each other. Any of the acoustic waveresonators shown in the drawings can be implemented by acoustic waveresonators in parallel with each other.

FIG. 22 is a schematic diagram of a multiplexer 220 with switchablefilters with termination impedances according to another embodiment. Themultiplexer 220 is like the multiplexer 210 of FIG. 21 , except that atermination impedance is connectable in parallel with each switchableacoustic wave resonator. The termination impedances of the multiplexer220 can include any suitable combination of features of the multiplexer210.

In the multiplexer 220, each unselected switchable acoustic waveresonator can be connected in parallel with a termination impedance. Themultiplexer 220 includes a first switchable filter 222 with a switchablecircuit 223. A switch 224 of the switchable circuit 223 can connect atermination impedance 225A or 225B in parallel with an unselected seriesacoustic wave resonator R7A or R7B, respectively. The multiplexer 220also includes a second switchable filter 226 with a switchable circuit227. A switch 228 of the switchable circuit 227 can connect atermination impedance 229A or 229B in parallel with an unselected shuntacoustic wave resonator R8A or R8B, respectively.

Switchable acoustic wave filters disclosed herein can be implemented inradio frequency systems. FIG. 23 is a schematic diagram of an exampleradio frequency system 230 with a multiplexer according to anembodiment. As illustrated, the radio frequency system includes anantenna 231, an antenna switch 232, an antenna-plexer 233 connectedbetween the antenna 231 and the antenna switch 232, at least oneduplexer 234, a receive switch 235, a transmit switch 236, a low noiseamplifier 237, and a power amplifier 238. The antenna-plexer 233 caninclude one or more switchable acoustic wave filters in accordance withany suitable principles and advantages disclosed herein. Theantenna-plexer 231 can be electrically connected to the antenna 231 atan antenna port. The duplexer 234 can include one or more switchableacoustic wave filters in accordance with any suitable principles andadvantages disclosed herein.

In the radio frequency system 230, the antenna 231 can transmit andreceive RF signals. The antenna-plexer 233 can provide frequency domainmultiplexing for signals propagating between the antenna 231 and radiofrequency signal paths. One such radio frequency signal path includesthe antenna switch 232. The antenna switch 232 can selectiveelectrically connect a multiplexer or a standalone filter to theantenna-plexer 233. As illustrated, the antenna switch 232 can selectiveelectrically connect the duplexer 234 to the antenna-plexer 233. Theduplexer 234 includes a receive filter configured to filter a radiofrequency signal received by the antenna 231 and to provide a filteredradio frequency signal to the low noise amplifier 237 via a receiveswitch 236. The low noise amplifier 237 can amplify the filtered radiofrequency signal. The duplexer 234 also includes a transmit filterconfigured to filter a radio frequency signal generated by the poweramplifier 238 for transmission by the antenna 231. The power amplifier238 can amplify a radio frequency signal. The transmit switch 236 canconnect the power amplifier 238 to the transmit filter of the duplexer234.

The switchable acoustic wave filters disclosed herein can be implementedin wireless communication devices. FIG. 24 is a schematic block diagramof a wireless communication device 240 that includes a switchableacoustic wave filter according to an embodiment. The wirelesscommunication device 240 can be a mobile device. The wirelesscommunication device 240 can be any suitable wireless communicationdevice. For instance, a wireless communication device 240 can be amobile phone, such as a smart phone. As illustrated, the wirelesscommunication device 240 includes a baseband system 241, a transceiver242, a front end system 243, one or more antennas 244, a powermanagement system 245, a memory 246, a user interface 247, and a battery248.

The wireless communication device 240 can be used communicate using awide variety of communications technologies, including, but not limitedto, 2G, 3G, 4G (including LTE, LTE-Advanced, and/or LTE-Advanced Pro),5G NR, WLAN (for instance, Wi-Fi), WPAN (for instance, Bluetooth and/orZigBee), WMAN (for instance, WiMax), and/or GPS technologies.

The transceiver 242 generates RF signals for transmission and processesincoming RF signals received from the antennas 244. Variousfunctionalities associated with the transmission and receiving of RFsignals can be achieved by one or more components that are collectivelyrepresented in FIG. 24 as the transceiver 242. In one example, separatecomponents (for instance, separate circuits or dies) can be provided forhandling certain types of RF signals.

The front end system 243 aids in conditioning signals provided to and/orreceived from the antennas 244. In the illustrated embodiment, the frontend system 243 includes antenna tuning circuitry 250, power amplifiers(PAs) 251, low noise amplifiers (LNAs) 252, filters 253, switches 254,and signal splitting/combining circuitry 255. However, otherimplementations are possible. The filters 253 can include one or moreswitchable acoustic wave filters in accordance with any suitableprinciples and advantages disclosed herein.

The front end system 243 can provide a number of functionalities,including, but not limited to, amplifying signals for transmission,amplifying received signals, filtering signals, switching betweendifferent bands, switching between different power modes, switchingbetween transmission and receiving modes, duplexing of signals,multiplexing of signals, or any suitable combination thereof.

In certain implementations, the wireless communication device 240supports carrier aggregation, thereby providing flexibility to increasepeak data rates. Carrier aggregation can be used for Frequency DivisionDuplexing (FDD) and/or Time Division Duplexing (TDD), and may be used toaggregate a plurality of carriers and/or channels. Carrier aggregationincludes contiguous aggregation, in which contiguous carriers within thesame operating frequency band are aggregated. Carrier aggregation canalso be non-contiguous, and can include carriers separated in frequencywithin a common band or in different bands.

The antennas 244 can include antennas used for a wide variety of typesof communications. For example, the antennas 244 can include antennasfor transmitting and/or receiving signals associated with a wide varietyof frequencies and communications standards.

In certain implementations, the antennas 244 support MIMO communicationsand/or switched diversity communications. For example, MIMOcommunications use multiple antennas for communicating multiple datastreams over a single radio frequency channel. MIMO communicationsbenefit from higher signal to noise ratio, improved coding, and/orreduced signal interference due to spatial multiplexing differences ofthe radio environment. Switched diversity refers to communications inwhich a particular antenna is selected for operation at a particulartime. For example, a switch can be used to select a particular antennafrom a group of antennas based on a variety of factors, such as anobserved bit error rate and/or a signal strength indicator.

The wireless communication device 240 can operate with beamforming incertain implementations. For example, the front end system 243 caninclude amplifiers having controllable gain and phase shifters havingcontrollable phase to provide beam formation and directivity fortransmission and/or reception of signals using the antennas 244. Forexample, in the context of signal transmission, the amplitude and phasesof the transmit signals provided to the antennas 244 are controlled suchthat radiated signals from the antennas 244 combine using constructiveand destructive interference to generate an aggregate transmit signalexhibiting beam-like qualities with more signal strength propagating ina given direction. In the context of signal reception, the amplitude andphases are controlled such that more signal energy is received when thesignal is arriving to the antennas 244 from a particular direction. Incertain implementations, the antennas 244 include one or more arrays ofantenna elements to enhance beamforming.

The baseband system 241 is coupled to the user interface 247 tofacilitate processing of various user input and output (I/O), such asvoice and data. The baseband system 241 provides the transceiver 242with digital representations of transmit signals, which the transceiver242 processes to generate RF signals for transmission. The basebandsystem 241 also processes digital representations of received signalsprovided by the transceiver 242. As shown in FIG. 24 , the basebandsystem 241 is coupled to the memory 246 of facilitate operation of thewireless communication device 240.

The memory 246 can be used for a wide variety of purposes, such asstoring data and/or instructions to facilitate the operation of thewireless communication device 240 and/or to provide storage of userinformation.

The power management system 245 provides a number of power managementfunctions of the wireless communication device 240. In certainimplementations, the power management system 245 includes a PA supplycontrol circuit that controls the supply voltages of the poweramplifiers 251. For example, the power management system 245 can beconfigured to change the supply voltage(s) provided to one or more ofthe power amplifiers 251 to improve efficiency, such as power addedefficiency (PAE).

As shown in FIG. 24 , the power management system 245 receives a batteryvoltage from the battery 248. The battery 248 can be any suitablebattery for use in the wireless communication device 240, including, forexample, a lithium-ion battery.

Any of the embodiments described above can be implemented in associationwith mobile devices such as cellular handsets. The principles andadvantages of the embodiments can be used for any systems or apparatus,such as any uplink wireless communication device, that could benefitfrom any of the embodiments described herein. The teachings herein areapplicable to a variety of systems. Although this disclosure includesexample embodiments, the teachings described herein can be applied to avariety of structures. Any of the principles and advantages discussedherein can be implemented in association with RF circuits configured toprocess signals having a frequency in a range from about 30 kHz to 300GHz, such as in a frequency range from about 400 MHz to 8.5 GHz or in afrequency range from about 400 MHz to 5 GHz.

Aspects of this disclosure can be implemented in various electronicdevices. Examples of the electronic devices can include, but are notlimited to, consumer electronic products, parts of the consumerelectronic products such as packaged radio frequency modules, uplinkwireless communication devices, wireless communication infrastructure,electronic test equipment, etc. Examples of the electronic devices caninclude, but are not limited to, a mobile phone such as a smart phone, awearable computing device such as a smart watch or an ear piece, atelephone, a television, a computer monitor, a computer, a modem, ahand-held computer, a laptop computer, a tablet computer, a microwave, arefrigerator, a vehicular electronics system such as an automotiveelectronics system, a robot such as an industrial robot, an Internet ofthings device, a stereo system, a digital music player, a radio, acamera such as a digital camera, a portable memory chip, a homeappliance such as a washer or a dryer, a peripheral device, a wristwatch, a clock, etc. Further, the electronic devices can includeunfinished products.

Unless the context indicates otherwise, throughout the description andthe claims, the words “comprise,” “comprising,” “include,” “including”and the like are to generally be construed in an inclusive sense, asopposed to an exclusive or exhaustive sense; that is to say, in thesense of “including, but not limited to.” Conditional language usedherein, such as, among others, “can,” “could,” “might,” “may,” “e.g.,”“for example,” “such as” and the like, unless specifically statedotherwise, or otherwise understood within the context as used, isgenerally intended to convey that certain embodiments include, whileother embodiments do not include, certain features, elements and/orstates. The word “coupled”, as generally used herein, refers to two ormore elements that may be either directly connected, or connected by wayof one or more intermediate elements. Likewise, the word “connected”, asgenerally used herein, refers to two or more elements that may be eitherdirectly connected, or connected by way of one or more intermediateelements. Additionally, the words “herein,” “above,” “below,” and wordsof similar import, when used in this application, shall refer to thisapplication as a whole and not to any particular portions of thisapplication. Where the context permits, words in the above DetailedDescription using the singular or plural number may also include theplural or singular number respectively.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the disclosure. Indeed, the novel resonators, filters,multiplexer, devices, modules, wireless communication devices,apparatus, methods, and systems described herein may be embodied in avariety of other forms. Furthermore, various omissions, substitutionsand changes in the form of the resonators, filters, multiplexer,devices, modules, wireless communication devices, apparatus, methods,and systems described herein may be made without departing from thespirit of the disclosure. For example, while blocks are presented in agiven arrangement, alternative embodiments may perform similarfunctionalities with different components and/or circuit topologies, andsome blocks may be deleted, moved, added, subdivided, combined, and/ormodified. Each of these blocks may be implemented in a variety ofdifferent ways. Any suitable combination of the elements and/or acts ofthe various embodiments described above can be combined to providefurther embodiments. The accompanying claims and their equivalents areintended to cover such forms or modifications as would fall within thescope and spirit of the disclosure.

What is claimed is:
 1. A multiplexer with a switchable acoustic wavefilter, the multiplexer comprising: a first filter configured to receivea radio frequency signal, the first filter including one or moreacoustic wave resonators, switchable acoustic wave resonators, and aswitch configurable into at least a first state and a second state, theswitch configured to select a different subset of the switchableacoustic wave resonators to filter the radio frequency signal togetherwith at least the one or more acoustic wave resonators in the firststate than in the second state; and a second filter connected to thefirst filter.
 2. The multiplexer of claim 1 wherein the second state isassociated with co-existence, and the first filter has lower performanceassociated with an operating band for the second state relative to thefirst state.
 3. The multiplexer of claim 2 wherein the first filter is aband pass filter having a pass band, and the pass band covers a smallerfrequency range for the second state relative to the first state.
 4. Themultiplexer of claim 2 wherein the first filter is a band stop filterhaving a stop band, and the stop band covers a smaller frequency rangefor the second state relative to the first state.
 5. The multiplexer ofclaim 1 wherein the switchable acoustic wave resonators include seriesresonators.
 6. The multiplexer of claim 1 wherein the switchableacoustic wave resonators include shunt resonators.
 7. The multiplexer ofclaim 1 wherein a band edge of the first filter and a band edge of thesecond filter are closer in frequency in the first state of the switchthan in the second state of the switch, the first state being associatedwith associated with the second filter being inactive and the secondstate being associated with co-existence.
 8. The multiplexer of claim 1wherein the second filter includes a second switch and second switchableacoustic wave resonators.
 9. The multiplexer of claim 8 wherein thefirst filter is configured to move a band edge of a frequency responseof the first filter by toggling the switch between the first state andthe second state, and the second filter is configured to move a bandedge of a frequency response of the second filter with the secondswitch.
 10. The multiplexer of claim 8 further comprising aninductor-capacitor circuit coupled between both the first filter and thesecond filter and an antenna node of the multiplexer, theinductor-capacitor filter configured to attenuate a harmonic generatedby the switch.
 11. The multiplexer of claim 1 wherein the first filteris a band pass filter and the second filter is a band stop filter. 12.The multiplexer of claim 1 wherein the first filter is a band stopfilter and the second filter is a band pass filter.
 13. The multiplexerof claim 1 wherein the first filter and the second filter are band passfilters.
 14. The multiplexer of claim 1 wherein the first filterincludes a second switch and second switchable acoustic wave resonators.15. The multiplexer of claim 1 wherein the first filter and the secondfilter are configured to filter radio frequency signals associated withdifferent frequency bands, and the different frequency bands include awireless local area network band and a cellular band.
 16. Themultiplexer of claim 1 wherein the first filter and the second filterhave respective band edges that are within 5 megahertz of each other.17. The multiplexer of claim 1 wherein the different subsets include afirst subset and a second subset, the first subset consisting of a firstswitchable acoustic wave resonator, and the second subset consisting ofa second switchable acoustic wave resonator.
 18. The multiplexer ofclaim 1 wherein the first filter has a single switch loss.
 19. Awireless communication device comprising: an antenna switch; an antenna;and an antenna-plexer including a first filter and a second filtercoupled to the first filter, the first filter being in a signal pathbetween the antenna switch and the antenna, the first filter configuredto receive a radio frequency signal, the first filter including one ormore acoustic wave resonators, switchable acoustic wave resonators, anda switch configurable into at least a first state and a second state,the switch configured to select a different subset of the switchableacoustic wave resonators to filter the radio frequency signal togetherwith at least the one or more acoustic wave resonators in the firststate than in the second state.
 20. A switchable filter comprising: oneor more acoustic wave resonators; switchable acoustic wave resonators;and a switch configurable into at least a first state and a secondstate, the switch configured to select a different subset of theswitchable acoustic wave resonators to filter a radio frequency signaltogether with at least the one or more acoustic wave resonators in thefirst state than in the second state.